In strawberry raising, particularly in Florida, it is advantageous to market new strawberries as early in the season as possible, typically in late January and early February, at which time a premium is paid for the strawberries. During the normal harvest season, prices for strawberries may be two-thirds less than the price for strawberries available during the early market.
Traditionally, strawberries are grown in dikes formed of raised banks of soil formed by a machine. The dikes have a base width typically of 31 inches and a top width of typically 28 inches at a height of 8 inches above the base. Inclined side walls join the top and base to form a trapezoid shaped dike.
A single piece of opaque plastic sheeting, such as polyethylene, and referred to as a mulching sheet or strip, is stretched across the dikes, and typically has a thickness of 2 to 5 mils. The plastic sheeting eliminates weeds and retains water entrapped below the plastic sheeting. Approximately every twelve inches in the plastic sheeting, a hole is punched and a strawberry seedling is inserted through the hole during the early weeks of October. Irrigation of the dikes may be provided by drip irrigation lines which are laid along the length of the dikes
A problem with the raising of strawberries is that if the temperature of the soil falls below a certain temperature, typically 42.degree. F., the progress of growth of the strawberry is arrested. The delay in growth affects the availability of the mature strawberries for early market which could result in obtaining a seasonal price for strawberries rather than the much greater early market price. Further, if the strawberries are subjected to wind or temperature less than 33.degree. F. the berries of the plant are usually lost.
To avoid the loss of berries at a temperature of less than 33.degree. F., a fine mist of well water is sprayed onto the plants. As the temperature dips below 33.degree. F. and the water freezes, the freezing of the thin layer of water produces a loss of heat which is transferred to the plant to maintain the berries at a temperature above 33.degree. F. This slight amount of ice formation does not hurt the berries in any way. However, due to water rationing, water is not always available for protecting the young strawberries during unseasonable bouts of cold weather.
Previous attempts to provide an improved mulching sheet or strip are disclosed in U.S. Pat. No. 4,833,822 to DiGrassi, U.S. Pat. No. 3,205,619 to Henry and U.S. Pat. No. 3,206,892 to Telkes et al. These patents disclose a tube of water located spaced from a seedling so as to anchor a mulching strip with respect to a single row of seedlings.
These patents disclose systems with limited use in expansive fields of strawberries for protecting strawberry seedlings and other crops, arranged in at least two rows at a peak of a dike.